diff --git a/source/filesys/fsperm.c b/source/filesys/fsperm.c
index aea904d..45379a8 100644
--- a/source/filesys/fsperm.c
+++ b/source/filesys/fsperm.c
@@ -8,7 +8,8 @@
 #define PATH_SYS_LVL1   "S:/twln.bin", "S:/twlp.bin" 
 #define PATH_SYS_LVL2   "1:/rw/sys/LocalFriendCodeSeed_B", "1:/rw/sys/LocalFriendCodeSeed_A", \
                         "1:/rw/sys/SecureInfo_A", "1:/rw/sys/SecureInfo_B", \
-                        "1:/private/movable.sed", "S:/ctrnand_fat.bin", "S:/ctrnand_full.bin"
+                        "1:/private/movable.sed", "1:/ro/sys/HWCAL0.dat", "1:/ro/sys/HWCAL1.dat", \
+                        "S:/ctrnand_fat.bin", "S:/ctrnand_full.bin"
 #define PATH_SYS_LVL3   "S:/firm0.bin", "S:/firm1.bin", "S:/nand.bin", "S:/nand_minsize.bin", "S:/nand_hdr.bin", \
                         "S:/sector0x96.bin", "S:/twlmbr.bin"
 #define PATH_EMU_LVL1   "E:/ctrnand_fat.bin", "E:/ctrnand_full.bin", "E:/nand.bin", "E:/nand_minsize.bin", "E:/nand_hdr.bin"
diff --git a/source/nand/essentials.h b/source/nand/essentials.h
index 4edc547..16573f3 100644
--- a/source/nand/essentials.h
+++ b/source/nand/essentials.h
@@ -10,6 +10,9 @@
 // magic number for essential backup
 #define ESSENTIAL_MAGIC 'n', 'a', 'n', 'd', '_', 'h', 'd', 'r', 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00
 
+// size of /ro/sys/HWCAL0.dat and /ro/sys/HWCAL1.dat
+#define SIZE_HWCAL 0x9D0
+
 // /rw/sys/LocalFriendCodeSeed_B (/_A) file
 // see: http://3dbrew.org/wiki/Nandrw/sys/LocalFriendCodeSeed_B
 typedef struct {
@@ -44,13 +47,17 @@ typedef struct {
     ExeFsHeader header;
     u8 nand_hdr[0x200];
     SecureInfo secinfo;
-    u8 padding_secinfo[0x200 - sizeof(SecureInfo)];
+    u8 padding_secinfo[0x200 - (sizeof(SecureInfo)%0x200)];
     MovableSed movable;
-    u8 padding_movable[0x200 - sizeof(MovableSed)];
+    u8 padding_movable[0x200 - (sizeof(MovableSed)%0x200)];
     LocalFriendCodeSeed frndseed;
-    u8 padding_frndseed[0x200 - sizeof(LocalFriendCodeSeed)];
+    u8 padding_frndseed[0x200 - (sizeof(LocalFriendCodeSeed)%0x200)];
     u8 nand_cid[0x10];
     u8 padding_nand_cid[0x200 - 0x10];
     u8 otp[0x100];
     u8 padding_otp[0x200 - 0x100];
+    u8 hwcal0[SIZE_HWCAL];
+    u8 padding_hwcal0[0x200 - (SIZE_HWCAL%0x200)];
+    u8 hwcal1[SIZE_HWCAL];
+    u8 padding_hwcal1[0x200 - (SIZE_HWCAL%0x200)];
 } __attribute__((packed)) EssentialBackup;
diff --git a/source/nand/nandutil.c b/source/nand/nandutil.c
index c2525b5..47e99ef 100644
--- a/source/nand/nandutil.c
+++ b/source/nand/nandutil.c
@@ -27,12 +27,14 @@ u32 ReadNandFile(FIL* file, void* buffer, u32 sector, u32 count, u32 keyslot) {
 u32 BuildEssentialBackup(const char* path, EssentialBackup* essential) {
     // prepare essential backup struct
     ExeFsFileHeader filelist[] = {
-        { "nand_hdr", 0x000, 0x200 },
-        { "secinfo" , 0x200, 0x111 },
-        { "movable" , 0x400, 0x140 },
-        { "frndseed", 0x600, 0x110 },
-        { "nand_cid", 0x800, 0x010 },
-        { "otp"     , 0xA00, 0x100 }
+        { "nand_hdr", 0x0000, 0x200 },
+        { "secinfo" , 0x0200, 0x111 },
+        { "movable" , 0x0400, 0x140 },
+        { "frndseed", 0x0600, 0x110 },
+        { "nand_cid", 0x0800, 0x010 },
+        { "otp"     , 0x0A00, 0x100 },
+        { "hwcal0"  , 0x0C00, 0x9D0 },
+        { "hwcal1"  , 0x1600, 0x9D0 }
     };
     memset(essential, 0, sizeof(EssentialBackup));
     memcpy(essential, filelist, sizeof(filelist));
@@ -59,16 +61,22 @@ u32 BuildEssentialBackup(const char* path, EssentialBackup* essential) {
         return 1;
     }
     
+    // HWCAL0.dat / HWCAL1.dat
+    if ((fvx_qread("7:/ro/sys/HWCAL0.dat", &(essential->hwcal0), 0, 0x1000, (UINT*) &(files[6].size)) != FR_OK) ||
+        (fvx_qread("7:/ro/sys/HWCAL1.dat", &(essential->hwcal1), 0, 0x1000, (UINT*) &(files[7].size)) != FR_OK)) {
+        memset(&(filelist[6]), 0, 2 * sizeof(ExeFsFileHeader));
+    }
+    
     // mount original file
     InitImgFS(path_bak);
-        
+    
     // fill nand cid / otp hash
     if (GetNandCid(&(essential->nand_cid)) != 0) return 1;
-    if (!IS_UNLOCKED) memset(&(filelist[5]), 0, sizeof(ExeFsFileHeader));
+    if (!IS_UNLOCKED) memset(&(filelist[5]), 0, 3 * sizeof(ExeFsFileHeader));
     else memcpy(&(essential->otp), (u8*) 0x10012000, 0x100);
     
     // calculate hashes
-    for (u32 i = 0; i < (IS_UNLOCKED ? 6 : 5); i++) 
+    for (u32 i = 0; i < 8 && *(filelist[i].name); i++) 
         sha_quick(essential->header.hashes[9-i],
             ((u8*) essential) + files[i].offset + sizeof(ExeFsHeader),
             files[i].size, SHA256_MODE);